Ignition and fuel supply control apparatus for fluid fuel pot-types burners



Filed April 2, 1951 R. F. VAN TUBERGEN IGNITION AND FUEL SUPPLY CONTROL'APPARATUS FOR FLUID FUEL POT-TYPES BURNEIRS Aug. 30, 1955 INVENTOR. jxa flffl a/zwaggg ATmP/vEY United States Patent 0 IGNITION AND FUEL SUPPLY CONTROL APPARATUS FOR FLUID FUEL POT-TYPES BURNERS Richard F. Van Tubergen, Portland, Oreg. Application April 2, 1951, Serial No. 218,721 11 Claims. (Cl. 158-28) cause of drafts occurring Within the combustion chamher. This problem is particularly acute during the initial period of operation immediately following the light-- ing of the burner and before the burner and the combustion chamber have become thoroughly heated. It is complicated by the fact that any reignition means employed should not become. active immediately following the snuff out while the burner is still hot, since an explosive gaseous mixture is present therein. It is complicated further because the ignition'means should not be active when the burner is flooded with a large quantity of oil. which might occur when the snuff out takes place during a period of power failure, whereupon oil flows to the burner but is not consumed thereby.

In my copending patent application, Serial No. 129,941, filed November 29, 1949, now Patent No. 2,688,999, granted September 14, 1954, I have disclosed oil burner control apparatus which is successful in meeting the above problems. The apparatus described in that application is adapted, however, for use with a manually controlled oil burner, and it is a primary object of the present invention to provide fuel supply and ignition control apparatus which may be used in conjunction with thermostatically operated burners as Well as with those which are operated manually.

It is another object of this invention to provide ignition and fuel supply control apparatus for fluid fuel burners which will ignite the burner in the first instance and will operate effectively during the period immediately following the initial ignition of the burner, re-

igniting it automatically in the event that it should be snuffed out.

It is another important object of the present invention to provide ignition and fuel supply control apparatus for fluid fuel burners which automatically will reignite snuffed out burners without hazard of an explosion from accumulated combustible gases.

It is another object of this invention to provide ignition and fuel supply control apparatus for fluid fuel burners which apparatus will shut off the supply of oil to the burner in the event of a power failure before a dangerous amount thereof has accumulated, and which automatically will reignite the burner upon resumption of power service.

It is another object of the present invention to provide ignition and fuel supply control apparatus for fluid fuel burners which apparatus is completely automatic in admitting fuel to the burner and igniting it, reigniting the burner if a snuff out should occur, inactivating the ignition means when the burner is hot, and reducing the fire to pilot fire level, when heat no longer is required in the area to be heated.

Still another object of the present invention is the provision of ignition. and fuel supply control apparatus for fluid fuel burners which apparatus is remarkably simple in construction, easy to install and operate, reliable in operation, and requiring a minimum of attention during use. p I

The manner which the foregoing and other objects of this invention are accomplished will be apparent from the accompanying specification and claims considered together with the drawings wherein:

Figure 1 is a schematic view illustrating the ignition and fuel supply control apparatus of this invention as applied to a thermostatically controlled oil burner assembly, the thermostat being illustrated in back elevation;

Figure. 2 is a front elevation of the thermostat of Figure 1;

Figure 3 is a schematic thermostat of Figure 1; and v Figure 4 is a fragmentary diagrammatic view taken along the lines 44 of Figure 1. 1

Generally stated, the presently described ignition and fuel supply control apparatus, as applied to the conventional oil burner supplied with valve means for controlling the flow of oil to the burner, comprises a thermostat stationed in the room to be heated. In an electric circuit with the thermostat is a heat motor to which a first electric switch is physically connected. The heat motor may include a bimetal blade having for its function the closing of the electric switch and also the adjustment of the burner valve to pilot fire position. In series with the first electric switch is an electric ignition element view in side elevation of the stationed adjacent the burner and adapted to ignite the same when the switch is closed, as when the thermostat is adjusted below room temperature. Temperature responsive means such as a second bimetal blade is sta-' tioned adjacent the burner and is actuatable at a predetermined temperature level of the same. A second electric switch is associated with the temperature responsive means in such a manner that the second switch is opened after the burner has reached the desired level. The second switch is in series circuit relationship with the ignition element so that with opening of the switch the ignition element will be de-energized until such time as the burner again is below the predetermined temperature level.

Also associated with the temperature responsive means, as by being mounted thereon, is a third electric switc This switch is normally open and is electrically connected to a second heat motor which may comprise an electric resistor and a bimetal blade placed in heat exchange relation thereto. The latter blade is operable to adjust the fuel control valve between pilot fire and full fire positions. Therefore, when the third electric switch is closed by operation of the temperature responsive means associated with the burner, the fuelsupply valve will be opened and the burner will be on full fire. This condition Will continue until the thermostat is satisfied, whereupon the second heat motor will be deenergized, permitting the fuel supply valve to return to its pilot fire position; 7

Considering the foregoing in greater detail and with particular reference to the drawings:

In Figure l the burner pot of an oil burner is indicated generally at 10. This unit may be of conventional construction, being provided with burner ring 12 and fuel inlet 14. The latter is connected through conduit 16 to metering valve 18 for supplying oil or other fluid fuel to the burner at a controlled rate. Valve 18 may be supplied with fuel from any suitable source through conduit 20.

When igniting the burner, oil fed to it through conduit 16 flows out on the floor of burner pot 10. There it is picked up by a wick 22 made of reinforced woven asbestos, or similar non-combustible absorbent material, and contained in perforated holder 24. Holder 24 is formed at its rear terminal portion with a knuckle 26 which is'adapted' to receive the ignition element 23'. The latter element passes through a plug 30 penetrating the sidewall or the burner and the fire pot. It is energized through an electric circuit to be described in detail hereinafter, but including electrical conductors 32, 34 conmeeting the ignition element to a transformer 3'6 capable of supplying currentat a suitable voltage to the element, e. g. a voltage of about 2 volts.

In this manner the ignition element may be located a safe distance above the burner and the fi'oor of the burner pot, preferably being placed just below the fire ring 12 where his shielded by the same. In this position it is out of the carbonizi'ng zone and in the coolest part of the burner pot, which greatly prolongs its service lite as otherwise it would tend to crystallize and break with: use.

Valve 18 employed for supplying fuel at a controlled rate to burner 14' may be of the class wherein a spring pressed plunger permits adjustment of the valve to a selected one of three positions, i. e. closed, pilot fire and full fire. Thus, valve .18 comprises a reservoir which may be partially filled with oil and which contains a cylinder 40 communicating with conduit 16. Cylinder 4 is formed with a centrally positioned valve seat 42 and with suitably positioned ports 44 adapted to pass oil to the interior of the cylinder. Slidably mounted within cylinder 40 is a valve plunger or stem 46 adapted to seat in seat- 42;

The upper portionof plunger 46 is formed with or attached to. the head member 48 which has an" area of reduced diameter adapted to seat the coil spring 50; The latter encircles cylinder 40 and; being under compression, urges plunger 46 outwardly, thereby tending to open thevalve, permitting the passage of fuel through port 44into= the lower portion of the cylinder and thence into conduit 16.

Means are provided invalve 18 for adjusting the plunger 46 to its various positions. To this end there is provided a bar 52 which is pivotally attached to a bracket 53 which in turn is attached to the housing of the valve. The freeendof bar 52 bears against the upper end of plunger 46. stationed transversely across the top of bar 52 is a: pivotally or resiliently mounted bar- 54-. stationed above the latter bar, and positioned in adirection parallel tobar 52' is still another bar 56 whichmay be suitably attached to bracket 53 mounting bar 52.

Bar 56 serves as a stop to limit the axial movement of plunger 46, stationing the latter in pilot fire position. For this purpose the bar. is provided with a projection 58 adapted to bear against the contact member or pin 601 extending transversely of and carried by the bimetal blade 62. The latter together with the electric resistance element 64 form a heat motor mounted on the valve casing and connected to a source of el'ectriecurrent.

To assist in the adjustment ofplunger 46 to a selected one of its various positionsthere is provided a hold down member or rod 66. This member is slidably mounted in bearing 68 penetrating the housing of the valve and extends in a direction parallel to that of plunger 46. The lower end of rod 66 carries horizontal bar 54 while the upper end engages an arm 70 attached to a bimetalblade 72 which together with the electric resistance element 74 form another heat motor. The latter may be mounted in asuitable manner as by being placed within a housing 76 placed on top of valve 18. Like resistor 64, resistor 74 is connected to a source of electric current in a manner to be explained hereinbelow.

Resistors 64 and 74 provide means for automatically adjusting plunger 46 to any one of its three positions. When the elements comprising the valve control assembly are. in the position illustrated in Figure 1, the plunger is positioned so that it entirely closes the valve. U'pon 4 upward movement of arm 70, however, which occurs when resistor 74' is energized, rod 66 and plunger46 move upwardly until bar 54 engages bar 56. The valve then will be in partially opened or pilot fire position. Then when bar 56 is released, which occurs when bimetal blade 62 moves upwardly upon energization of electric resistor 64, further upward movement of the plunger is permitted until the valve is in its wide open or full fire position.

Manual means for controlling the action of the valve also are provided. As is indicated in Figure 4, a vertical rod 80 penetrating the housing of valve 18 may be stationed directly above bars 52, 54 and 56. Rod 80 may be provided with any suitable means for securing its axial displacement, as bymeans of a cam or screw associated with the control handle 82. This means is conventional and is not illustrated in detail. However, upon turning handle 82, rod. 80 is moved. downwardly, until it engages bar 56. This in turn holds plunger 46 in its position of maximum downward displacement so that valve. 18 remains fully closed irrespective of any subsequent energization of heat motors 64 and 74.

Also associated with the burner assembly and valve in the presently described control apparatus is a thermostat indicated schematically at 83. Thermostat 83 is located. in the room area tov be, heated, and may be of conventional construction. Thus it may comprise a bimetall blade 84 provided at one endwith a contact point 85 and mounted at the other of its ends onthe support member 86. Opposed to contact member 85. is another contact member 87 mounted on the support member 83. The distance separating contact points 85 and 87 may be adjusted by means of a camof conventional construction. (not illustrated) associated with a calibrated dial ht). Contact point 85 is connected through conductor 92 to terminal 94 while contact 87 is connected through conductor 96 to terminal 98. p

Also included in the thermostat assembly is an electrically conducting arm- 100 attached to dial 20 and r0.- tatable together with the latter about the pivotal mount.- ing,10-2. Arm 100- has at its free end a contact point 104 which is adapted to engage a contactplate 106. The latter is of discontinuous construction providing an area wherein contact point 104 will touch a nonconducting material (oiF position), whereupon the circuit is open and the entire system is de-energized, and a conducting area which will complete anelectric circuit when contact; point 104: is] in contact therewith on position), energizing the system. Arm 1% is connected through con doctor 10% to terminal 1-10,, while cont-act plate 106. is connected through conductor 112 to. terminal 114.

The presently described automatic control apparatusis correlated with the above. described burner assembly,

.. valve and thermostat in a manner which now will bedescribed;

Meausfirst areprovidedl for opening valve 18 toits-pilot fire position, for energizing the ignition element 28, and for maintaining the ignitiorr element energized during the initial ignition periodwhen the dial 90 oft-he thermostat is' adjusted so that it is in tl1e"on position, with point 1% contacting plate 166. To this end there is provided an electric switch 12% which is associated withthc bimetal blade-7'2. Switch isnormally open; and is in an electric circuit with ignition element 28 through transformer 36'. Although a variety ofswitches may be enrployed, a mercury switch preferably is used of the class wherein tilting of the switch results in making or breaking an electric circuit.

Although switch 120 may be mounted directly upon the. bimctal' blade 72, its. action can be made more, sensitive by. mounting; it upon a, second bimetal blade I22 attached to. blade 72 through pin 124. Blade 122 pref} erably is in direct contact with blade. 72, so that. the. thermal conductivity of. the. latter transmits, heatit'ronrthe resistance element 74 to the blade 122. Since the lattersupports only switch 120, it may be of relatively light construction, as compared with the heavy blade 72 required to control plunger 46 of the valve. Hence it is relatively sensitive to thermal changes and moves through a wire arc upon being heated and cooled. This motion then makes the circuit through switch 120 before the valve is opened appreciably. It willbe apparent that when the circuit is made, ignition element 28 will be energized and when the circuit through switch 120 is broken, element 28 will become de-energized.

Although it is desired to maintain ignition element 28 energized during the initial combustion period so that fuel entering the burner will automatically be reignited following snuff-outs, it is desirable to de-energize the ignition 7 element after the initial ignition period and the snufl-out hazard have passed. For this purpose temperature responsive means are employed to break the ignition element circuit after the desired time interval, e. g. 7 minutes, has elapsed.

The temperature responsive means in the illustrated embodiment comprises a bimetal blade 130 in heat exchange relationship to the burner pot and mounted thereon through bracket 132. Another bracket 134 is attached to the bimetal blade 130 adjacent its free end, and attached to or operable by this bracket is another electric switch. The latter preferably comprises a mercury switch 136 which normally is in closed position and which is in an electric circuit with switch 120 and ignition element 28. Hence at the beginning of the operation, the circuit may be completed through the ignition element upon closing normally open switch 120. However, after the initial combustion period is over, bimetal blade 130 will be activated, opening switch 134, breaking the circuit and de-energizing the ignition element.

During the initial combustion period it is desirable that valve 18 remain in pilot fire position. However, after the expiration of this period, the valve should be opened to its full fire position. The presently described means for accomplishing this purpose comprises an electric switch associated with the bimetal blade 130 and adapted when closed to energize heat motor 64. This, in turn, permits the opening of valve 18 to full fire position.

In the illustrated embodiment, this switch comprises the mercury switch 140, which, like switch 136, may be carried on bracket 134. Switch 140 is normally open. However, as the bimetal blade 130 arcs downwardly after the burner has become warm, switch 140 will be closed,

completing the circuit to heat motor 64 and opening valve U adjust dial 90 of the thermostat so that it is in the on E position. This will bring contact 104 on arm 100 in contact with plate 106. A circuit then will be closed from house lines 142, 144 through transformer 146, which reduces the voltage from 110 volts to an appropriate level, 12 volts for example. The current then traverses conductors 148, 150 and 108, arm 100 (dotted line position), contact plate 106 and conductors 112 and 152. It then passes through resistor 74, conductor 154 and thence back to transformer 146.

When the foregoing circuit has been established, the heat generated by resistor 74 bends bimetal blade 72 upwardly, carrying with it arm 70 and switch 120. This accomplishes two results. First, it permits the raising of spring pressed plunger 46 until its motion is arrested by stop member 56. This in turn opens valve 18 to its pilot fire position.

The movement of bimetal blade 72 also closes the normally open switch 120, which initiates a flow of current from house line 142 through conductor 156, switch 136,

6 conductor 158, switch 120, conductor 160, transformer 36, and thence via conductors 162, 164 back to house line 144. This energizes ignition element 28, which remains energized during the initial combustion period to reignite the burner should a snufl-out occur.

However, after the initial combustion period is over, bimetal blade 130 arcs downwardly, thereby opening the normally closed mercury switch 136. This breaks the circuit including ignition element 28 so that the latter is de-energized and remains so until the bimetal blade 130 returns to its normal position.

Although the downward arcing of bimetal blade 130 opens normally closed switch 136, it closes the normally open switch 140. This in turn initiates an electric circuit through conductors 148, 170, 96 and across contact points 85, 87, which will be closed when the thermostat has been adjusted to a temperature above room temperature. The current then will flow through conductor 92,.terminal 94, conductor 172, electric resistor 64, conductor 174, switch 140 andconductor 176.

Energization of resistor 64 induces the upward arcing of bimetal blade 62 which permits the upward movement of stop 66, this in turn permitting the further upward movement of spring pressed plunger 46 and opening valve 18 to its full fire position.

The burner will continue to operate at full fire until one of several contingencies occurs. In the event that a snuff-out inadvertently should occur, even at full fire, the bimetal blade 130 would return to its normal position upon cooling of the burner. This would open switch 140 which in turn would de-energize electric resistor 64, returning the valve 18 to its pilot fire po sition. It also would close switch 136, energizing the ignition element 28 which would reignite the burner.

If a power failure should occur the entire circuit would be broken. After cooling of the burner, however, the bimetal blade 130 would return to its normal position, opening switch 140 and closing switch 136 so that, upon the resumption of power service, valve 40 would remain in its pilot fire position and ignition element 28 would be activated for reignition of the burner.

When, as in the usual case, the system operates at full fire until the thermostat is satisfied, the bimetal blade 84 of the latter will separate contact points 85 and 87 breaking the circuit through the resistor 64. Bimetal blade 62 then will return to its normal position, adjusting valve 18 to pilot fire position; The system then will remain at pilot fire, with ignition element 28 de-energized (unless a snufi? out should occur), until the thermostat again demands heat.

When the thermostat dial is adjusted to the off position, contact point 104 is moved away from plate 106, breaking the circuit including resistor 74. As a result, blade 72 completely closes valve 18 and opens switch 120. Also blade 130 upon returning to its normal po sition after cooling of the burner will close switch 136 and open switch 140. The entire system thus will be inactivated until such time as dial is adjusted to the on position.

Thus it will be apparent that by the present invention 1 have provided an ignition and fuel supply control apparatus for fluid fuel burners, which, while simple in construction and involving a minimum of constituent parts, efiectively controls the operation of the burner so that it operates reliably and safely. By the operation of my apparatus, the burner is ignited automatically after snuff-outs without any hazard whatsoever of explosion due to accumulated combustible vapors, or of the ignition of a large quantity of oil which may have accumulated within the burner pot. In addition the control is operable even in the event of a power failure, and lends itself for combination with a manual control if such is desired.

It is to be understood that the form of my invention,

herewith shown and described, is to be taken as a prefer-red example of the same, and that various changes in the shape, size and arrangement of the parts may be resorted to, without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. Ignition and fuel supply control apparatus for fluid f-uel pot-type burners comprising in combination a burner pot, valve means for upplying fuel to said burner pot, room temperature thermostat switch means, an electrically operable heat motor, an electric circuit including the heat motor and thermostat switch means, a first electric switch mechanically connected to the heat motor, an electric circuit including said first electric switch, an electrically operable ignition element placed in operative relations to the burner pot and in the electric circuit with the first switch, temperature responsive means mounted in heat exchange relation with the outer side of the burner pot and actuatable at a pre-determined temperature level of the burner pot, a second switch mechanically connected to the temperature responsive means and in the electric circuit with the ignition element, the heat motor being mechanically associated with the valve means and first switch to open the valve means and close the first switch when said heat motor is energized, thereby energizing the ignition element, and the temperature responsive means being mechanically associated with the second switch to open the second switch and to tie-energize the ignition element when the burner pot has reached said predetermined temperature level.

2. The ignition and fuel supply control apparatus of claim 1 wherein the heat motor includes a bimetal blade connected to the valve means and the first electric switch comprises a mercury switch mounted on the bimetal blade.

3. The ignition and fuel supply control apparatus of claim 1 wherein the temperature responsive means comprises a bimetal blade and the second switch comprises a mercury switch mounted on the bimetal blade.

4. The ignition and fuel supply control apparatus of claim 1 wherein the heat motor includes a first bimetal blade mechanically associated with the valve means, the first electric switch comprises a mercury switch mounted upon the first bimetal blade, the temperature responsive means comprises a second bimetal blade, and the second electric switch comprises a mercury switch mounted upon the second bimetal blade.

5. Ignition and fuel supply control apparatus for fluid fuel pot-type burners comprising in combination a burner pot, valve means for supplying fuel to said burner pot, said valve means including a spring pressed plunger for regulating the flow of fluid through the valve, room temperature thermostat switch means, an electric resistance element, an electric circuit including said resistance element and thermostat switch means, a bimetal blade in heat exchange relation with the electric resistance element and positioned to operate the spring pressed plunger of the valve, a first electric switch stationed adjacent the bimetal blade and operable by the movement of the same, an electric circuit including said first electric switch, an electrically operable ignition element stationed in operative relation to the burner pot and in the electric circuit with the first switch, temperature responsive means mounted in heat exchange relation with the outer side of the burner pot and actuatable at a pre-determined temperature level of the burner pot, and a second electric switch mechanically connected to the temperature responsive means and in the electric circuit with the i gnitionelement, thebimetal blade being mechanically associated with the valve means and first switch to close the first electric switch and to open the valve means and to energize the ignition element when said resistance element is energized and when the thermostat circuit is closed, and the temperature responsive means being mechanically associated with the secondswitch to open the second switch and to de-energize the ignition element when the burner pot has reached said pro-determined temperature level.

6. Ignition and fuel supply control apparatus for fluid fuel pot-type burners comprising in combination a burner pot, valve means for supplying fuel to said burner pot, said valve means including a spring pressed plunger for regulating the flow of fluid through the valve, room temperature thermostat switch means, an electric resistance element, an electric circuit including said resistance element and thermostat switch means, a bimetal blade in heat exchange relationship with the electric resistance element and positioned to operate the spring pressed plunger of the valve, a second bimetal blade in heat exchange relation with the first bimetal blade, the second bimetal blade being more heat responsive than the first, a first electric switch mounted on the second bimetal blade and operable by the movement of the same, an electric circuit including said first electric switch, an electrically operable ignition element stationed in operative relation to the burner pot and in the electric circuit with the first switch,

temperature responsive means mounted in heat exchange relation with the outer side of the burner pot and actuatable at a pre-determined temperature level of the burner pot, and a second electric switch mechanically connected to the temperature responsive means and in the electric circuit with the ignition element, the bimetal blade being mechanically associated with the valve means and first switch to close the first electric switch and to open the valve means and to energize the ignition element when said resistance element is energized and when the thermostat circuit is closed, the first electric switch being closed before substantial opening of the valve, and the temperature responsive means being mechanically associated with the second switch to open the second electric switch and to tie-energize the ignition element when the burner pot has reached said pro-determined temperature level. I '7. Ignition and fuel supply control apparatus for fluid fuel pot-type burners comprising in combination a burner pot, valve means for supplying fuel to said burner pot, said valve means being adjustable between pilot fire and full fire positions, room temperature thermostat switch means, an electrically operable heat motor, an electric circuitincluding said heat motor and thermostat switch means, a first electric switch mechanically connected to the heat motor, an electric circuit including said first electric switch, an electrically operable ignition element placed in operative relation to the burner pot and in the electric circuit with the first switch, temperature responsive means mounted in heat exchange relation with the outer side ofthe burner pot and actuatable at a pre-determined temperature level of the burner pot, a second electric switch mechanically connected to the temperature responsive means and in the electric circuit with the ignition element, a second electrically operable heat motor, an electric circuit including said second heat motor, and a third electric switch mechanically associated with the heat responsive means and in the electric circuit with the second heat motor, the first heat motor being mechanically associated with the valve means and first switch and operable when energized when the thermostat circuit is closed to close the first electric switch and to open the valve means to pilot fire position and to energize the ignition element, the temperature responsive means being mechanically associated with the second and third switches and operable when the burner pot has reached that predetermined level to open the second electric switch for deenergizing the ignition element and to close the third switch for energizing the second heat motor, the second heat motor being mechanically associated with the valve means and operable when the burner pet has reached said pro-determined temperature level to adjust the valve means to its full fire position.

8. The ignition and fuel supply control apparatus of claim 7 wherein the temperature responsive means com prises a bimetal blade and the third electric switch comprises a mercury switch mounted thereon.

9. Ignition and fuel supply control apparatus for fluid fuel pot-type burners comprising in combination a burner pot, valve means for supplying fuel to said burner pot, said valve means including a spring pressed plunger adjustable to pilot fire and full fire positions, room temperature thermostat switch means, an electrically operable heat motor, an electric circuit including said heat motor and thermostat means, a first electric switch mechanical y associated with the heat motor, an electric circuit including said first electric switch, an electrically operable ignition element placed in operative relation to the burner pot and in the electric circuit with the first electric switch, temperature responsive means mounted in heat exchange relation with the outer side of the burner pot and actuatable at a pre-determined temperature level of the burner pot, a second electric switch mechanically connected to the temperature responsive means and in the electrical circuit with the ignition element, a bimetal blade and re. electric resistance element arranged in heat exchange relation, the blade being mechanically associated with the valve means for adjusting the same between pilot and full fire positions, and a third electric switch mechanically associated with the temperature responsive means and in the electric circuit with the electric resistance element, the heat motor being mechanically associated with the valve means and first switch and operable when energized to close the first switch and to open the valve means to pilot fire position and to energize the ignition element when the thermostat circuit is closed, and the tempera.- ture responsive means being mechanically associated with the second and third switches and operable when the burner pot has reached the said predetermined temperature to open the second electric switch and de-energize ignition element and to close the third electric switch and energize the electric resistance element.

10. Ignition and fuel supply control apparatus for fluid fuel pot-type burners comprising in combination a burner pot, valve means for supplying fuel to said burner po. the valve means including a spring pressed plunger adjustable to pilot fire and full fire positions, room temperature thermostat switch means, a first electric resistor, an electric circuit including said first electric resistor and said thermostat switch means, a first bimetal blade in heat exchange relationship with the first electric resistor, a first electric switch mechanically associated with and operable by the movement of the first bimetal blade, an electric circuit including said first electric switch, an electrically operable ignition element placed in operative relation to the burner pot and in the electric circuit with the first electric switch, temperature responsive means mounted in heat exchange relation with the outer side of the burner pot and actuatable at a pre-determined temperature level of the burner pot, a second electric switch mechanically associated with and operable by the temperature responsive means and in the electric circuit with the ignition element, a second bimetal blade, a second electric resistor in heat exchange relationship with the second bimetal blade, an electric circuit including said second electric resistor, a third electric switch in the circuit of the second resistor and stationed adjacent the temperature responsive means and operable thereby, the second bimetal blade being positioned to engage and adjust the spring pressed plunger of the valve between pilot and full fire positions; the first bimetal blade being mechanically associated with the first switch and operable to close the first electric switch and energize the ignition element when the first resistor is energized when the thermostat circuit is closed, the temperature responsive means being mechanically associated with the second and third switches and operable when the burner pot has reached the pre-determined temperature level to open the second switch and de-energize the ignition element, and also to close the third electric switch and energize the second electric resistor, thereby actuating the second bimetal blade for adjustment of the'plunger to full fire position.

11. Ignition and fuel supply control apparatus for fluid fuel pot-type burners comprising in combination a burner pot, valve means for supplying fuel to said burner pot, the valve means being adjustable to pilot fire and full fire positions, a room temperature thermostat switch including a manual switch and a temperature actuated switch, electrical circuits for said switches, a first electrically operable heat motor in the circuit of the manual switch, a first electric switch mechanically connected to the first heat motor, an electric circuit including said first electric switch, an electrically operable ignition element placed in operative relation to the burner pot and in the circuit of the first electric switch, temperature responsive means mounted in heat exchange relation with the outer side of the burner pot and actuatable at a pre-determined temperature level of the burner pot, a second electric switch mechanically connected to the temperature responsive means and in the circuit of the ignition element, a second electrically operable heat motor in the circuit of the thermostat temperature actuated switch, and a third electric switch mechanically connected to the temperature responsive means and in the circuit of the second heat motor, the first heat motor being mechanically associated with the valve means and first electric switch and operable when energized when the thermostat manual switch is closed to close the first electric switch and to open the valve means to pilot fire position and to energize the ignition element, the temperature responsive means being mechanically associated with the second and third electric switches and operable when the burner pot has reached said pre-determined level to open the second electric switch for derenergizing the ignition element and to close the third electric switch for energizing the second heat motor, the second heat motor being mechanically associated with the valve means and operable when the burner pot has reached said pre-determined temperature level and When the thermostat temperature actuated switch is closed to adjust the valve means to its full fire position.

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